Stored energy in a battery may be used for a variety of applications from nanodevices, minidevices, consumer electronics, computers, defense, automotive, marine, and aerospace applications. In vehicle applications, the energy from the battery may be used solely to power devices or vehicles or may be used in combination with other power sources such as AC power, fuel cells, or combustion engines. The energy from the battery may be utilized to power a variety of such devices, included but not limited to, electric motors, drivetrains and the like.
In the operation of such devices, it may be desirable to know the remaining energy in the battery or the “state of charge” (SOC). The SOC refers to the stored energy in the battery that is available to be used at any given time relative to the stored energy that is available when the battery is fully charged. An accurate determination of the SOC allows for the device or vehicles to maximize performance and efficiency. An accurate determination of the SOC also allows for a determination as to whether or not energy from the battery should be utilized to perform a particular task in combination with an alternative power source such as a combustion engine or fuel cell, or whether a particular task can be completed using only energy from the battery.